On the map question, I actually did some searching. Couldn't find any British maps, but I did find one printed in 1914 by Rand McNally&Co, an American company:
Image:LA2-NSRW-1-0148.jpg - Wikipedia, the free encyclopedia
I believe this is printed just after Dalai announced Tibetan independence.
Also relevant is the 1922 Times World atlas, on pg 17-18, on
David Rumsey's Site
This is the recognized political map at the time, 8 years after Tibet announced its independence. As can be clearly seen, it's still lumped with China. Note: I actually think this one is British, is Bartholomew and J.G. a British company?
As for international recognition of Tibet at the time, as stated in
A History of Tibet by Alex McKay - Tibet enjoyed
de facto independent recognition and full independent state treatment. So, according to this book (which had quite a lot of relevant primary sources,) Tibet was never OFFICIALLY recognized by the League of Nations. The Brits wanted to, but China and Russia kept getting in the way. So technically the modern state of Tibet was never officially recognized, I searched and could not find ONE nation that publicly acknowledged its existence.